Halting nine days of attacks, Israel and Hamas agreed to a "humanitarian" pause to allow food, water, and supplies to be delivered to Palestine on Thursday. But after only two hours of stillness, Israeli rocket alarms wailed as mortar shells fired from Hamas landed in the southern part of the country, breaching the five-hour ceasefire. The window, brokered by the United Nations, began at 10 a.m. and ends at 3 p.m. local time with the understanding that both sides would hold off on attacks.

While it is unclear if Israel will strike back at Hamas, it previously promised to retaliate "firmly and decisively" if Hamas attacked during the window. After Israel announced its cooperation with the plan on Wednesday, Hamas spokesperson Sami Abu Zuhri said that the militants would also respect the respite.

Israel has remained quiet thus far, but time is ticking to see if the cease fire will hold after the mortar shells. However, so far, the ceasefire has appeared to hold.

Before the window began Thursday morning, officials from the Israeli military said it stopped a major attack from Gaza, as 13 militants used an underground tunnel to emerge onto Israeli territory. The militants were attacked by the Israeli military from the air, but officials say it is "not immediately clear" if they were killed. Hamas, meanwhile, claimed responsibility for the attack on its website and said that the militants were only fired on after "completion of its mission," and had had safely returned to Gaza.

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This is the second attempt at a Israel-Hamas cease fire. Though Israel signed off on the deal led by Egypt on Tuesday and halted fire for six hours, Hamas refused and launched more rockets into Israel, ultimately unraveling the plan.

Israeli Prime Minister Benjamin Netanyahu disparaged Hamas' refusal to cooperate. “Hamas chose to continue fighting and will pay the price for that decision,” Netanyahu told press on Tuesday evening. “When there is no cease-fire, our answer is fire.”